Senior Quantitative Software Engineer (Product and Platform)

We're looking for a senior software engineer with a quantitative background to own end-to-end feature development across our frontend and backend systems. You'll work with all layers of the stack: our React/Next.js frontend applications, our core Python services, the API layer, the computation engine underneath, and the infrastructure that runs it all. You'll collaborate with a cross-functional team of economists, developers, and machine learning specialists to bring ideas from concept to production.

Responsibilities

• Frontend development: Build responsive, data-intensive interfaces in React + TypeScript (Next.js), with effective state management and a focus on great user experience.
• Backend systems: Design, develop, and ship APIs and services in Python (FastAPI); contribute to a shared pricing library and a DAG-based computation engine; develop logic for our core services which coordinate, orchestrate, and execute the calculations consumed by our user-facing applications.
• Pricing models: productionalize, maintain, and optimize asset pricing models; build and maintain associated data pipelines.
• Data modeling and performance: Structure and validate data, profile bottlenecks, and tune performance of the calculation engine at scale.
• Authentication and security: Implement secure, user-friendly auth flows and protect sensitive customer data.
• Infrastructure and deployment: Build and maintain the containerized services and infrastructure that run the platform, contributing to CI/CD, deployments, and observability.
• Collaboration & ownership: Partner cross-functionally to scope features, mentor peers, and contribute to technical direction.

• 5+ years building production-grade web applications.
• Bachelor's degree in Computer Science, Engineering, or a related field, or equivalent practical experience. Graduate degree preferred.
• Strong fluency in TypeScript/React (Next.js a plus), with real experience owning or shipping at least one frontend application end-to-end, and strong fluency in Python.
• Proficiency in Python web frameworks (FastAPI or similar), with the ability to design and maintain APIs and services in a shared codebase.
• Comfort working with data and scientific computing libraries (Pandas, Numpy, Pydantic); experience working with ML libraries such as TensorFlow or PyTorch is a plus.
• Familiarity with authentication standards (HTTPS, JWT, OAuth).
• A solid grounding in databases (PostgreSQL, BigQuery, MongoDB, Redis, or similar) and messaging systems (RabbitMQ or equivalent) is a plus.
• Exposure to financial modeling concepts, valuation methodologies, or pricing frameworks (e.g., discounted cash flow models, asset pricing, risk analytics) is a plus.
• Experience with containerized deployments and infrastructure (Docker, Kubernetes, Helm, or similar) is a plus.
• Strong problem-solving skills, ownership mindset, and the ability to thrive in a fast-moving startup environment.
• Excellent communication skills; able to work across disciplines and explain complex ideas simply.

At Delfi, we're building the next generation of financial analytics and marketplace products. Our platform helps banks, credit unions, and other financial institutions make data-driven decisions, powered by advanced econometrics and AI/ML. As an early team member, you'll have outsized influence on our product, architecture, and culture., Why Join Delfi? * Shape products at the frontier of financial analytics and risk management. * High ownership, high impact role: your code will power real features used by customers. * True full stack scope: own features across the frontend, the API layer, and the computation engine rather than being boxed into one side of the stack. * Work with a small, experienced, and ambitious team where learning and growth are encouraged. * Join one of the most exciting and award-winning fintech startups at an early stage.